Little River County is a county located in the U.S. state of Arkansas. As of 2000, the population was 13,628. The county seat is Ashdown. Little River County is Arkansas's 59th county, formed from Sevier County on March 5, 1867 and named for the Little River. The county is separated from all other surrounding counties in the state by water (a characteristic shared only with neighboring Miller County), with the Little River, Millwood Lake and the Red River forming the boundaries of the county within the state.